3-4 shift=bad vibration

[collisiontech]

Hello, I have a bad vibration during 3-4 shift in my `98 mountaineer.The harder you acelerate the worse the vibration,but if you back of the gas right before the shift it will not do it.when it does it it only lasts a second then stops.When I hooked scanner to it and drove it the tcc reads 100% twords the end of 3rd and stays at 100% during the shift to 4th when the vibration happens,when it dont do it the tcc backs off to around 55% during the shift.I'm thinking maybe the tcc selonoid, any input would be great,thanks

 

[mcpherson]

U-joints possibly since you say it stops once you back off the gas.

 

[BrooklynBay]

Try to adjust the bands.

 

[collisiontech]

I've already checked them, and they're good. I guess it's more of a really bad tc chatter that vibrates the whole truck for a second. It's more like getting on the freeway type aceleration that it does it, only during the shift then stops and only in 3-4 shift.

 

[BrooklynBay]

Is it more like a shift flare with a high RPM, and slippage?

 

[collisiontech]

bands adj

The bands can cause the tcc not to back off during the shift? I need to read more of youre posts,Ill try it.I'm not a tranny guy,steering and frame angles is more my feild.

 

[collisiontech]

I cant feel any slippage

 

[BrooklynBay]

Does it feel like a delay, then a sudden grab, then a feeling like it's slowly dropping out of gear? If so, then it could have dried out servos. This is a common problem since the proximity of the servos are so close to the catalytic converter. Do you have a heat shield in front of them in good condition?

 

[collisiontech]

Thats close to it BrooklynBay,I ran the scan tool on it again today and the PCS is only at 10psi at idel in gear with my foot on the brake,60 in park.I'm starting to think it needs rebilt.Maybe a good reason for a T-5 and manual t-case.

 

[BrooklynBay]

A low pressure reading could mean that the valve body gaskets are blown, valve body bolts are loose, the boost valve is stuck, or the EPC is not regulating the proper amount of pressure.

 

[collisiontech]

OK,one more scan.With the key on engine off,and cold,the epc is reading 10psi,is this right,is it a base reading? Is it a bad epc? or is it something else?

 

[BrooklynBay]

I'm surprised that it's showing any pressure with the engine off. The engine has to turn the internal oil pump to create pressure.